U.S. patent application number 16/789510 was filed with the patent office on 2020-08-13 for migration of nano metals in semisolid and solid matrix under the influence of selectively triggered heterogeneous nucleation and.
The applicant listed for this patent is Instituto Tecnologico y de Estudios Superiores de Monterrey. Invention is credited to Gaurav Chauhan, Vianni Chopra, Manish Madhukar Kulkarni, Marc J. Madou, Sergio Omar Martinez Chapa.
Application Number | 20200255287 16/789510 |
Document ID | 20200255287 / US20200255287 |
Family ID | 1000004675097 |
Filed Date | 2020-08-13 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200255287 |
Kind Code |
A1 |
Martinez Chapa; Sergio Omar ;
et al. |
August 13, 2020 |
MIGRATION OF NANO METALS IN SEMISOLID AND SOLID MATRIX UNDER THE
INFLUENCE OF SELECTIVELY TRIGGERED HETEROGENEOUS NUCLEATION AND
GROWTH
Abstract
Use of heterogeneous nucleation allows the localized reduction
of metal salt and also cross-link the carbon precursor in the same
region. This cross-linked matrix act as the secondary heterogeneous
sites for spontaneous Nano particle synthesis and growth during the
process of pyrolysis. Selectively creating heterogeneous sites and
reducing the metal precursor using highly focused energy beams
create various metal-carbon composites with controlled metal
positioning. This is such a unique process where a pretreatment
process will control the fabrication of complex metal-carbon
composite nano and microstructures. This greatly simplifies the
fabrication process, facilitating nanostructures like Nano metal
bulbs, nanometal pointed nanogaps and metal sandwich structures
with such process. With several advantages ranging from
electronics, catalysis, optics and several other
bio-functionalization technologies, this enables materials with
unique and hybrid advantages. Moreover, fabrication of micro and
Nano level structures provides a CMEMS and BIOMEMS relevant
approach for wide range of applications.
Inventors: |
Martinez Chapa; Sergio Omar;
(Monterrey, MX) ; Chauhan; Gaurav; (Monterrey,
MX) ; Madou; Marc J.; (Monterrey, MX) ;
Kulkarni; Manish Madhukar; (Monterrey, MX) ; Chopra;
Vianni; (Monterrey, MX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Instituto Tecnologico y de Estudios Superiores de
Monterrey |
Monterrey |
|
MX |
|
|
Family ID: |
1000004675097 |
Appl. No.: |
16/789510 |
Filed: |
February 13, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62805138 |
Feb 13, 2019 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B81C 2201/0149 20130101;
B81C 1/00007 20130101 |
International
Class: |
B81C 1/00 20060101
B81C001/00 |
Claims
1. A method for selective accumulation of nano-metals in a
semisolid and solid matrix as a composite, comprising pretreating a
substrate composition by applying focused energy to initiate
reduction of a metal precursor, and creating heterogeneous sites to
increase the kinetics of nucleation and growth.
2. The method of claim 1, wherein the precursor used for the
semisolid and solid matrix is selected from a group consisting of
biodegradable-non biodegradable polymers, positive and negative
photoresists, photosensitive polymers, thermos-sensitive polymers,
and combinations thereof.
3. The method of claim 1, wherein the nano-metals are metal
nanoparticles selected from a group consisting of gold, silver,
platinum, titanium, zinc, copper, aluminum, chromium, iron, cobalt,
tin nanostructures, and combinations thereof.
4. The method of claim 1, wherein the nanoparticles are the metal
oxide and ceramic nanostructures are selected from a group
consisting of titanium oxide, zinc oxide, silicon oxide, aluminum
oxide, aluminum nitride, copper oxide, iron oxide nanostructures,
and combinations thereof.
5. The method of claim 1, wherein a source of the focused energy is
selected from a group consisting of focused electron beam, one or
more photon beams, ultraviolet and infrared wavelength exposure,
focused heat treatment, and combinations thereof.
6. The method of claim 1, wherein the material is fabricated with
the selective growth and accumulation of nano metals on or inside
the solid or semisolid thin films, nano/micro fibers, suspended
nano/micro wires, microelectronic mechanical devices, flakes,
powder, nano/micro electrodes, and combinations thereof.
7. The method according to claim 5, wherein the selectively
fabricated composite material is functionalized with chemical,
biological groups/moieties and combinations thereof.
8. The method according to claim 7, wherein the chemical
functionalization of the surface includes
biodegradable/non-biodegradable polymers, dyes, therapeutic
chemicals, and lipids, cationic/ionic resins, cheating agents,
complexation moieties, and combinations thereof.
9. The method according to claim 7, wherein the biological
functionalization of the surface include proteins, enzymes,
antibodies, antigens, peptides, aptamers, nucleotides, nucleotides,
human/animal origin cells, microbes, viruses, and combinations
thereof.
10. The method according to claim 5, wherein the selectively
fabricated composite material presents enhances surface, bulk
conductivity, improved capacitance and surface kinetics for its
application as electrically and electrochemically relevant material
and sensing electrodes.
11. The method according to claim 5, wherein the selectively
fabricated composite material presents enhanced catalytic
performance.
12. The method according to claim 5, wherein the selectively
fabricated composite material presents a highly optically relevant
material for surface plasmon resonance, surface enhanced Raman
spectroscopy based analytical and sensing applications, plasmon
waveguides, tunable diffraction gratings and metamaterial based
applications.
13. The method according to claim 5, wherein the selectively
fabricated composite material presents applications in molecular
scale electronics, also called single-molecule electronics,
molecular transistor, bio-transistor and rectifiers (diodes) based
applications.
14. The method according to claim 5, wherein the selectively
fabricated composite material presents a highly biocompatible
material as a topical material, body implants or inserts for
applications including bio-sensing, drug delivery, bone and tissue
regeneration and support material, arterial stents, hernia meshes,
drug releasing coatings and cell culturing platforms.
15. The method according to claim 6, wherein the selectively
fabricated composite material is functionalized with chemical,
biological groups/moieties and combinations thereof.
16. The method according to claim 6, wherein the selectively
fabricated composite material presents enhances surface, bulk
conductivity, improved capacitance and surface kinetics for its
application as electrically and electrochemically relevant material
and sensing electrodes.
17. The method according to claim 6, wherein the selectively
fabricated composite material presents enhanced catalytic
performance.
18. The method according to claim 6, wherein the selectively
fabricated composite material presents a highly optically relevant
material for surface plasmon resonance, surface enhanced Raman
spectroscopy based analytical and sensing applications, plasmon
waveguides, tunable diffraction gratings and metamaterial based
applications.
19. The method according to claim 6, wherein the selectively
fabricated composite material presents applications in molecular
scale electronics, also called single-molecule electronics,
molecular transistor, bio-transistor and rectifiers (diodes) based
applications.
20. The method according to claim 6, wherein the selectively
fabricated composite material, presents a highly biocompatible
material as a topical material, body implants or inserts for
applications including bio-sensing, drug delivery, bone and tissue
regeneration and support material, arterial stents, hernia meshes,
drug releasing coatings and cell culturing platforms.
Description
OBJECT OF THE INVENTION
[0001] The invention discloses a novel technique for the selective
accumulation of the nano-metals in a semisolid and solid matrix,
where the substrate composition is pretreated by focused energy
source to initiate the reduction of metal precursor as well as
creating heterogeneous sites to increase the kinetics of nucleation
and growth. Energy sources includes focused electron and photon
(two or three photons) beams that provides a precisely controllable
pretreatment for nano and micro sized features. This approach is
precisely controllable depending on the process optimization and
accuracy of the energy source used. This invention unlocks the
possibility to fabricate metal-carbon composites with different
structures and configurations both at nano, mico as well as macro
scales. Some of the finest outcomes with this technology is the
creation of metal-carbon composite based nano and mico bulb,
metal-carbon sandwich, metal-carbon coaxial and core shell
structures. The invention covers a wide area of applications
ranging from nanoelectronics, smart sensing elements/transducers,
catalysis, optical transducers and antennas. Controlling the
nanometal localization inside a micro and nano structures further
allows its application as precise bimolecular sensor and even
single biomolecule or cell sensor.
Keyword:
[0002] Nanometal-carbon composite, heterogeneous nucleation,
photo-cross-linking, micro/nano bulb, metal carbon sandwich, metal
carbon coaxial.
BACKGROUND
[0003] Well-dispersed functional nanoparticles (NPs) in a
conductive carbon host are particularly important for sensors
applications. Electrochemical energy storage, electrochemical
catalysis, and photocatalysis, among other applications. The
conductive support cannot only effectively transport electrons and
heat generated during electrochemical reactions, but also disperse
the nanoparticles from severe aggregation. Along with that,
presence of nano-structures on the surface provides a perfect
platform for the chemical and biological functionalization. Two
main strategies have been developed for the synthesis of NPs
decorated on carbon-based materials, which includes
"synthesis-then-assembly" and in situ growth. For
synthesis-then-assembly methods, a suspension of synthesized
nanoparticles are introduced to the porous carbon matrix by
impregnation and then drying. More often, the NPs are prepared in
situ on a carbon support via chemical reduction or hydrothermal
reaction as a simple and low-cost method, and sometimes via
physical methods, such as electron beam radiation and selective
surface functionalization. Since carbon is non-wetting with most
metals and the interaction between metal NPs and carbon surface is,
weak the as-formed nanoparticles are prone to agglomerate and
redistribute during the synthesis and post heat treatments.
[0004] As the growth and aggregation of nanoparticles are time
dependent diffusion and migration processes, it is critical to
synthesize ultrafine NPs over a short time and quench the process
to prevent or, at least, minimize agglomeration. While conventional
high temperature synthesis methods, such as spray pyrolysis and
combustion, are fast (several seconds to minutes), a well
controllable heating method is desirable for the control of both
the high temperature heating process and also the resultant
particle size and distribution.
[0005] The arrangement of nanoparticles in a specific dimension and
position is key for their unique electrical, optical, magnetic
properties and the phenomena such as light propagation in
nanoparticles crystals and plasmonic resonance. For the
optimization of device performance, crucial parameters include the
nanoparticle size--and the inter particle distance, as well as the
arrangement controlling the coupling effects. Recent developments
in self-assembly techniques have opened interesting perspectives to
create motifs with desirable inter-particle distance. Methods such
as reverse micelles, microemulsions, Langmuir Blodgett films,
organometallic techniques, and two-phase liquid-liquid systems have
been used for 2D nanoparticle patterning on a substrate. Other
techniques, such as micro-contact printing, direct deposition by
photochemical decomposition and inkjet printing, offer a valuable
complement for fabrication. Among all architectures, the 3D
arrangement of nanoparticles remains one of the most challenging
goals due to stabilization problems. In order to create a
mechanically robust 3D structure, nanoparticles must first be
arranged through successive self-assembly and then sintered at
elevated temperature. Another approach for the formation of stable
3D arrangements of nanoparticles with proper inter-particle
distances to embed them in a matrix, typically a polymer. This
approach has limitations due to the complicated dispersion of
nanoparticles in a viscous polymers or the aggregation of
nanoparticles.
[0006] Fabrication of metallic nano-structures with in a dielectric
host material allows the optical response of the composite material
to be tailored, potentially achieving responses not possible in a
homogeneous material. Most experimentally realized negative index
metamaterials have been fabricated using "top-down" lithographic
techniques, usually either electron beam lithography (EBL) or
focused-ion-beam lithography (FIBL). Although these approaches can
provide resolution on the scale of a few nanometers, they are
inherently serial in nature and are limited to the fabrication of
relatively small samples, typically with high-cost and
low-throughput. A more recent approach to meta-materials involves
direct laser writing in a polymeric structure followed by metal
evaporation over the fabricated surface. While this method is
promising, full metal coverage is challenging. A need exists for
new fabrication methods that overcome the aforementioned
limitations.
BRIEF DESCRIPTION OF EACH FIGURE
[0007] FIG. 1. Schematic of the basic mechanism representing the
use of focused energy beam to create heterogeneous nucleation
sites.
[0008] FIG. 2. Schematic of the Nano-bulb fabrication process on a
nanofiber.
[0009] FIG. 3. Schematic of the nano-metal writing on precursor
thin films.
[0010] FIG. 4. Scanning electron microscopy of the gold Nano-bulbs
fabricated in the carbon nanofibers.
[0011] FIG. 5. Nanometal decorated nanogaps created by two
different methods where the properties and surface composition of
nanogaps is controlled by inducing metal accumulated nanogaps in
the center of suspended carbon based nanofiber.
DETAILED DESCRIPTION OF THE INVENTION
[0012] This invention opens a new prospective of controlling and
localizing the metal nanoparticles nucleation and growth on as well
as inside a substrate. The process relies on a precise pretreatment
of the precursor substrate mixture with a focused energy beam. The
localization and accumulation of the nano-metals is an in situ
process during the carbonization of the pretreated substrate. This
invention allows the selective growth of Nano metals in situ during
the transformation of the metal-carbon substrate into a nanometal
carbon composite. The process require a pretreatment process with
focused energy beam to create heterogeneous nucleation sites in the
metal-carbon substrate.
[0013] Writing metal structures or fabricating metal Nano
structures inside a solid matrix is a challenging process.
Researchers are using intense energy beam to reduce metal precursor
salts inside these solid or semisolid substrates. These processes
are very harsh, non-uniform and may damage the substrate
properties. A much easier solution is required to control and
localize this nanometal fabrication in a solid matrix like carbon,
which will further allow to reach the fabrication of structures
like metal carbon based Nano bulbs, sandwiches and coaxial/core
shell structures. Similar procedure. The problem relies in the fact
that all the researchers have tried the complete reduction of metal
precursors using high intensity/energy sources. No such research is
reported where passive accumulation of Nano metals is tried during
the process of substrate transformation.
Carbon MEM/NS (Microstructure and Nanostructures) Fabrication
[0014] This invention includes the fabrication of C-MEMS
microstructure and nano-structures scaled microelectronic devices
for wide range of application. One of the most prominent
application of this invention is the writing of predefined patterns
of metals/nano metals in a solid carbon matrix. These
microstructures are created by pretreating the photo cross-linking
polymer precursor containing metal precursor to create selective
nucleation (by virtue of site selective reduction of metal
precursor) as well as creation of secondary heterogeneous
nucleation and growth platform. This heterogeneous nucleation sites
further determines the patterning of the nanometal structures
inside the transforming carbon precursor from a polymer state to
solid carbon matrix during the process of high temperature
carbonization. As explained in FIG. 1, the heterogeneous nucleation
sites creation are responsible for the relatively higher nucleation
and growth of metal nano-structures. Diffusion rate of reduced
metal ions during the growth of nanostructure is highly dependent
on the concentration of metal ions and the diffusivity/porosity of
the surrounding matrix. This invention reports the selective
accumulation of metal ions around the self-created heterogeneous
sites resulting in the creation of 2D and 3D nano and
microstructures inside the solid carbon matrix. These structures
are represented as nano/micro bulb created on the suspended micro
or nano fibers/wires and writing with the nano/micro metal
structures on the surface and even inside the carbon matrix FIGS.
2, 3 and 4. 2D and 3D pretreatment using selective energy source
are used to create metal carbon sandwich structures and coaxial
structure of metal and carbon fibers/wires. Invention also presents
the fabrication of nano metals/metal pointed nanogaps fabricated on
the suspended nanofibers/wires. In molecular electronics,
individual molecules are integrated with the rest of the circuit by
positioning them in electrode gaps of the order of the molecule
size. Such nanoscale gaps (nanogaps) have emerged as important
experimental platforms for the electrical characterization of
molecules, capturing unique transport phenomena of both organic and
inorganic materials. These nanogaps are created using the
metal-carbon composite fibers/wires, which are designed to have an
accumulated metal/nanometal region at a certain region of the
suspended nano fiber/wire FIG. 5.
* * * * *